This invention relates generally to movable barrier operators for operating movable barriers or doors. More particularly, it relates to garage door operators having improved safety and energy efficiency features.
Garage door operators have become more sophisticated over the years providing users with increased convenience and security. However, users continue to desire further improvements and new features such as increased energy efficiency, ease of installation, automatic configuration, and aesthetic features, such as quiet, smooth operation.
In some markets energy costs are significant. Thus energy efficiency options such as lower horsepower motors and user control over the worklight functions are important to garage door operator owners. For example, most garage door operators have a worklight which turns on when the operator is commanded to move the door and shuts off a fixed period of time after the door stops. In the United States, an illumination period of 41/2 minutes is considered adequate. In markets outside the United States, 41/2 minutes is considered too long. Some garage door operators have special safety features, for example, which enable the worklight whenever the obstacle detection beam is broken by an intruder passing through an open garage door. Some users may wish to disable the worklight in this situation. There is a need for a garage door operator which can be automatically configured for predefined energy saving features, such as worklight shut-off time.
Some movable barrier operators include a flasher module which causes a small light to flash or blink whenever the barrier is commanded to move. The flasher module provides some warning when the barrier is moving. There is a need for an improved flasher unit which provides even greater warning to the user when the barrier is commanded to move.
Another feature desired in many markets is a smooth, quiet motor and transmission. Most garage door operators have AC motors because they are less expensive than DC motors. However, AC motors are generally noisier than DC motors.
Most garage door operators employ only one or two speeds of travel. Single speed operation, i.e., the motor immediately ramps up to full operating speed, can create a jarring start to the door. Then during closing, when the door approaches the floor at full operating speed, whether a DC or AC motor is used, the door closes abruptly with a high amount of tension on it from the inertia of the system. This jarring is hard on the transmission and the door and is annoying to the user.
If two operating speeds are used, the motor would be started at a slow speed, usually 20 percent of full operating speed, then after a fixed period of time, the motor speed would increase to full operating speed. Similarly, when the door reaches a fixed point above/below the close/open limit, the operator would decrease the motor speed to 20 percent of the maximum operating speed. While this two speed operation may eliminate some of the hard starts and stops, the speed changes can be noisy and do not occur smoothly, causing stress on the transmission. There is a need for a garage door operator which opens the door smoothly and quietly, with no aburptly apparent sign of speed change during operation.
Garage doors come in many types and sizes and thus different travel speeds are required for them. For example, a one-piece door will be movable through a shorter total travel distance and need to travel slower for safety reasons than a segmented door with a longer total travel distance. To accommodate the two door types, many garage door operators include two sprockets for driving the transmission. At installation, the installer must determine what type of door is to be driven, then select the appropriate sprocket to attach to the transmission. This takes additional time and if the installer is the user, may require several attempts before matching the correct sprocket for the door. There is a need for a garage door operator which automatically configures travel speed depending on size and weight of the door.
National safety standards dictate that a garage door operator perform a safety reversal (auto-reverse) when an object is detected only one inch above the DOWN limit or floor. To satisfy these safety requirements, most garage door operators include an obstacle detection system, located near the bottom of the door travel. This prevents the door from closing on objects or persons that may be in the door path. Such obstacle detection systems often include an infrared source and detector located on opposite sides of the door frame. The obstacle detector sends a signal when the infrared beam between the source and detector is broken, indicating an obstacle is detected. In response to the obstacle signal, the operator causes an automatic safety reversal. The door stops and begins traveling up, away from the obstacle.
There are two different "forces" used in the operation of the garage door operator. The first "force" is usually preset or setable at two force levels: the UP force level setting used to determine the speed at which the door travels in the UP direction and the DOWN force level setting used to determine the speed at which the door travels in the DOWN direction. The second "force" is the force level determined by the decrease in motor speed due to an external force applied to the door, i.e., from an obstacle or the floor. This external force level is also preset or setable and is any set-point type force against which the feedback force signal is compared. When the system determines the set point force has been met, an auto-reverse or stop is commanded.
To overcome differences in door installations, i.e. stickiness and resistance to movement and other varying frictional-type forces, some garage door operators permit the maximum force (the second force) used to drive the speed of travel to be varied manually. This, however, affects the system's auto-reverse operation based on force. The auto-reverse system based on force initiates an auto-reverse if the force on the door exceeds the maximum force setting (the second force) by some predetermined amount. If the user increases the force setting to drive the door through a "sticky" section of travel, the user may inadvertently affect the force to a much greater value than is safe for the unit to operate during normal use. For example, if the DOWN force setting is set so high that it is only a small incremental value less than the force setting which initiates an auto-reverse due to force, this causes the door to engage objects at a higher speed before reaching the auto-reverse force setting. While the obstacle detection system will cause the door to auto-reverse, the speed and force at which the door hits the obstacle may cause harm to the obstacle and/or the door.
Barrier movement operators should perform a safety reversal off an obstruction which is only marginally higher than the floor, yet still close the door safely against the floor. In operator systems where the door moves at a high speed, the relatively large momentum of the moving parts, including the door, accomplishes complete closure. In systems with a soft closure, where the door speed decreases from full maximum to a small percentage of full maximum when closing, there may be insufficient momentum in the door or system to accomplish a full closure. For example, even if the door is positioned at the floor, there is sometimes sufficient play in the trolley of the operator to allow the door to move if the user were to try to open it. In particular, in systems employing a DC motor, when the DC motor is shut off, it becomes a dynamic brake. If the door isn't quite at the floor when the DOWN travel limit is reached and the DC motor is shut off, the door and associated moving parts may not have sufficient momentum to overcome the braking force of the DC motor. There is a need for a garage door operator which closes the door completely, eliminating play in the door after closure.
Many garage door operator installations are made to existing garage doors. The amount of force needed to drive the door varies depending on type of door and the quality of the door frame and installation. As a result, some doors are "stickier" than others, requiring greater force to move them through the entire length of travel. If the door is started and stopped using the full operating speed, stickiness is not usually a problem. However, if the garage door operator is capable of operation at two speeds, stickiness becomes a larger problem at the lower speed. In some installations, a force sufficient to run at 20 percent of normal speed is too small to start some doors moving. There is a need for a garage door operator which automatically controls force output and thus start and stop speeds.